With approximately 165 million carats of diamonds still underground at the former Ekati diamond mine, its new owner, Burgundy Diamonds, is looking to extend the mine’s life by implementing a never-before tried method of kimberlite extraction.
“Not all of those (carats) will be recoverable. But even if we did get a big chunk of those carats, it potentially could extend the life of the asset for many, many years to come,” said Kim Truter, CEO of Burgundy Diamond Mines.
Considering the mine has the third largest endowment of diamonds on the planet, and is anticipated to become the seventh largest producer of diamonds in the world, Truter said finding new extraction techniques will be a strategic move in ensuring the longevity of the mine.
That method will involve a pilot project using underwater remote mining (URM) technology with an underwater remote vehicle to go beneath the surface of lakes and extract hard-to-reach kimberlite that might otherwise be cost prohibitive or difficult to obtain.
Truter said the process involves first smoothing out the underwater floor of the open pit and then implementing the three-part system of deploying the vehicle, or crawler, which will cut down into the kimberlite, then hydraulically pumping the kimberlite up to a floating platform on the surface. From there, the ore material will be transported to a dewatering/processing plant.
Hard challenges
The benefits of that method are multifold in comparison, Truter said.
“If you mine them using those conventional open pit underground methods, sometimes the water is a challenge, because from an environmental point of view, you’ve got to pump the water out or you’ve got to handle the water or do something about the water — so water can be a challenge,” he said.
“The second thing is the surrounding rock that typically, in the Northwest Territories, is granite. Now that is positive from an open pit point of view because it’s a very competent rock., which means that you can have very steep slope angles in a pit.”
“But it’s also hard work because you’ve got to obviously mine one of the hardest rocks on the planet to get at the pipe. So those are two challenges.”
The third challenge is access to energy, he said, as they must transport millions of litres of diesel fuel to power the site and the fleet of equipment.
Game changer
“When you put all those factors into the mix, a way of mining only the kimberlite pipe and not having to mine all the surrounding waste is a game changer,” said Truter. “Because what it would mean is you could only mine the kimberlite pipe, which is a couple of hundred meters in diameter.”
“It means your environmental footprint is dramatically reduced.”
As a result, while an open pit a kilometre wide must be dug for traditional kimberlite mining, the URM technology could reduce the size of the extraction area in a previously mined and flooded pit to as small as 150-metres wide.
“So, it’s a huge reduction in the environmental footprint. And potentially it might mean that you can lower the cost of extracting, which might mean that kimberlite pipes that could not be mined using the conventional way of doing it, suddenly become economic,” Truter explained.
“In the North, it could be a real game changer, because it means you might be able to go and mine whole other kimberlite pipes that you couldn’t mine using conventional methods,” he noted.
Testing innovation
But while the use of the submersible crawler technology is new to the diamond mining industry, many of its elements are already in use in different applications, such as seabed mining around the world, Truter said of the equipment developed by IHC Mining, a company based in the Netherlands.
Before the equipment becomes a permanent fixture on the NWT diamond mining landscape, however, many questions have to be answered about its suitability in the harsh Northern climate, he said of the process that will be implemented in two stages.
“As we answer those questions, we’ll slowly but surely get knowledge and then once we have, we might have multiple of these (underwater vehicles),” he said. “The first thing we want to do is to prove that the technology would work in our environment.”
The floor of the Lynx pit will be prepared by smoothing its underwater surface in 2024 and in mid-2025, the crawler will be deployed.
It also must be determined whether the system can operate only in warmer months or year round in the NWT.
Truter was reluctant to disclose the cost of such a system, citing competitive reasons.
Overall, he expressed optimism about the use of such technology in the future.
“I think it’s very important for the North that we find ways to extend these mines’ lives,” he said. “We can add to that the URM solution that helps us keep these mines going, which keeps jobs going, and taxes going.
For more stories from NWT & Nunavut Mining 2023, click this link: https://www.nnsl.com/special-feature-publications/special-feature-pdfs/2023-mining-supplement/